1,812 research outputs found

    Pathotypic diversity of Hyaloperonospora brassicae collected from Brassica oleracea

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    Downy mildew caused by Hyaloperonospora brassicae is an economically destructive disease of brassica crops in many growing regions throughout the world. Specialised pathogenicity of downy mildews from different Brassica species and closely related ornamental or wild relatives has been described from host range studies. Pathotypic variation amongst Hyaloperonospora brassicae isolates from Brassica oleracea has also been described; however, a standard set of B. oleracea lines that could enable reproducible classification of H. brassicae pathotypes was poorly developed. For this purpose, we examined the use of eight genetically refined host lines derived from our previous collaborative work on downy mildew resistance as a differential set to characterise pathotypes in the European population of H. brassicae. Interaction phenotypes for each combination of isolate and host line were assessed following drop inoculation of cotyledons and a spectrum of seven phenotypes was observed based on the level of sporulation on cotyledons and visible host responses. Two host lines were resistant or moderately resistant to the entire collection of isolates, and another was universally susceptible. Five lines showed differential responses to the H. brassicae isolates. A minimum of six pathotypes and five major effect resistance genes are proposed to explain all of the observed interaction phenotypes. The B. oleracea lines from this study can be useful for monitoring pathotype frequencies in H. brassicae populations in the same or other vegetable growing regions, and to assess the potential durability of disease control from different combinations of the predicted downy mildew resistance genes

    Approximating Node-Weighted k-MST on Planar Graphs

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    We study the problem of finding a minimum weight connected subgraph spanning at least kk vertices on planar, node-weighted graphs. We give a (4+\eps)-approximation algorithm for this problem. We achieve this by utilizing the recent LMP primal-dual 33-approximation for the node-weighted prize-collecting Steiner tree problem by Byrka et al (SWAT'16) and adopting an approach by Chudak et al. (Math.\ Prog.\ '04) regarding Lagrangian relaxation for the edge-weighted variant. In particular, we improve the procedure of picking additional vertices (tree merging procedure) given by Sadeghian (2013) by taking a constant number of recursive steps and utilizing the limited guessing procedure of Arora and Karakostas (Math.\ Prog.\ '06). More generally, our approach readily gives a (\nicefrac{4}{3}\cdot r+\eps)-approximation on any graph class where the algorithm of Byrka et al.\ for the prize-collecting version gives an rr-approximation. We argue that this can be interpreted as a generalization of an analogous result by K\"onemann et al. (Algorithmica~'11) for partial cover problems. Together with a lower bound construction by Mestre (STACS'08) for partial cover this implies that our bound is essentially best possible among algorithms that utilize an LMP algorithm for the Lagrangian relaxation as a black box. In addition to that, we argue by a more involved lower bound construction that even using the LMP algorithm by Byrka et al.\ in a \emph{non-black-box} fashion could not beat the factor \nicefrac{4}{3}\cdot r when the tree merging step relies only on the solutions output by the LMP algorithm

    Quantifying habitual levels of physical activity according to impact in older people: accelerometry protocol for the VIBE study

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    Physical activity (PA) may need to produce high impacts to be osteogenic. The aim of this study was to identify threshold(s) for defining high impact PA for future analyses in the VIBE (Vertical Impact and Bone in the Elderly) study, based on home recordings with triaxial accelerometers. Recordings were obtained from 19 Master Athlete Cohort (MAC; mean 67.6 years) and 15 Hertfordshire Cohort Study (HCS; mean 77.7 years) participants. Data cleaning protocols were developed to exclude artifacts. Accelerations expressed in g units were categorized into three bands selected from the distribution of positive Y-axis peak accelerations. Data were available for 6.6 and 4.4 days from MAC and HCS participants respectively, with approximately 14 hr recording daily. Three-fold more 0.5–1.0g impacts were observed in MAC versus HCS, 20-fold more 1.0–1.5g impacts, and 140-fold more impacts ≥ 1.5g. Our analysis protocol successfully distinguishes PA levels in active and sedentary older individuals

    Incidence of re-amputation following partial first ray amputation associated with diabetes mellitus and peripheral sensory neuropathy: a systematic review.

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    Diabetes mellitus with peripheral sensory neuropathy frequently results in forefoot ulceration. Ulceration at the first ray level tends to be recalcitrant to local wound care modalities and off-loading techniques. If healing does occur, ulcer recurrence is common. When infection develops, partial first ray amputation in an effort to preserve maximum foot length is often performed. However, the survivorship of partial first ray amputations in this patient population and associated re-amputation rate remain unknown. Therefore, in an effort to determine the actual re-amputation rate following any form of partial first ray amputation in patients with diabetes mellitus and peripheral neuropathy, the authors conducted a systematic review. Only studies involving any form of partial first ray amputation associated with diabetes mellitus and peripheral sensory neuropathy but without critical limb ischemia were included. Our search yielded a total of 24 references with 5 (20.8%) meeting our inclusion criteria involving 435 partial first ray amputations. The weighted mean age of patients was 59 years and the weighted mean follow-up was 26 months. The initial amputation level included the proximal phalanx base 167 (38.4%) times; first metatarsal head resection 96 (22.1%) times; first metatarsal-phalangeal joint disarticulation 53 (12.2%) times; first metatarsal mid-shaft 39 (9%) times; hallux fillet flap 32 (7.4%) times; first metatarsal base 29 (6.7%) times; and partial hallux 19 (4.4%) times. The incidence of re-amputation was 19.8% (86/435). The end stage, most proximal level, following re-amputation was an additional digit 32 (37.2%) times; transmetatarsal 28 (32.6%) times; below-knee 25 (29.1%) times; and LisFranc 1 (1.2%) time. The results of our systematic review reveal that one out of every five patients undergoing any version of a partial first ray amputation will eventually require more proximal re-amputation. These results reveal that partial first ray amputation for patients with diabetes and peripheral sensory neuropathy may not represent a durable, functional, or predictable foot-sparing amputation and that a more proximal amputation, such as a balanced transmetatarsal amputation, as the index amputation may be more beneficial to the patient. However, this remains a matter for conjecture due to the limited data available and, therefore, additional prospective investigations are warranted

    Controls on amorphous organic matter type and sulphurization in a Mississippian black shale

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    Paleoredox proxies (Fe speciation, trace element and δ34Spy) integrated with sedimentological and palynological observations link the distribution and type of particulate organic matter (OM) preserved to hydrocarbon source rock potential. In the Mississippian Bowland Shale Formation (Lancashire, UK), particulate OM is dominated by “heterogeneous” amorphous OM (AOM), primarily “sharp-edged, pellet-like” (AOMpel) and “heterogeneous, granular” (AOMgr) types. AOMpel is abundant in muds deposited under anoxic and moderately to highly sulphidic conditions and most likely represents the fecal minipellets of zooplankton and/or pellets of macro-zooplankters. We recognize two intervals, “A” and “B,” which exhibit Sorg/TOC > 0.04, suggesting a bulk Type II-S kerogen composition. The Interval A palynofacies is typified by pyritized AOMpel (AOMpyr) particles that contain high-relief organic spheres surrounding individual pyrite framboids, within each AOMpyr particle. These textures are interpreted as sulphurized OM local to pyrite framboids (Sorg-PF). Sorg-PF is rarely observed in Interval B, and absent in all other samples. Redox oscillation between ferruginous and euxinic conditions during early diagenesis of Interval A likely promoted S cycling in microenvironments surrounding pyrite framboids, which generated reactive S species and reactive OM required for sulphurization. Early diagenetic redox oscillation processes were apparently triggered by relative sea level fall, associated with an increased supply of FeHR from adjacent shelves into the basin. Interval B represents deposition during the late stages of basin infill and transition from anoxic to (sub)oxic bottom waters, where AOMpel is replaced by AOMgr as the dominant type of AOM. A large particle diameter at the limit of the mesh size (500 μm), sheet-like, fragmented character, and presence of candidate organic sheaths suggests AOMgr at least partially represent fragments of benthic microbial mats, probably as sulphide-oxidizers. A ternary plot of AOMpel + AOMpyr versus AOMgr versus spores + phytoclasts links the observed palynofacies to bottom and pore water redox conditions, water column productivity and proximity to fluvial (deltaic) supply of spores and phytoclasts. These variables were moderated by changing basin accommodation, driven primarily by eustatic sea level fluctuation. A sequence-stratigraphic control on AOM type and sulphurization is important for understanding the link between source rock heterogeneity and the timing of hydrocarbon generation and expulsion from this source rock

    Influenza A Virus Coding Regions Exhibit Host-Specific Global Ordered RNA Structure

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    Influenza A is a significant public health threat, partially because of its capacity to readily exchange gene segments between different host species to form novel pandemic strains. An understanding of the fundamental factors providing species barriers between different influenza hosts would facilitate identification of strains capable of leading to pandemic outbreaks and could also inform vaccine development. Here, we describe the difference in predicted RNA secondary structure stability that exists between avian, swine and human coding regions. The results predict that global ordered RNA structure exists in influenza A segments 1, 5, 7 and 8, and that ranges of free energies for secondary structure formation differ between host strains. The predicted free energy distributions for strains from avian, swine, and human species suggest criteria for segment reassortment and strains that might be ideal candidates for viral attenuation and vaccine development

    Factor analysis of self-treatment in diabetes mellitus: a cross-sectional study

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    <p>Abstract</p> <p>Background</p> <p>Self-treatment is a treatment of oneself without professional help, which may cause health-related consequences. This investigation examined the self-treatment behaviors in patients with diabetes mellitus in Iran/kashan.</p> <p>Methods</p> <p>The patients who referred to the clinic of diabetes and those who were admitted to the General hospital in the city of Kashan due to diabetes mellitus were asked to participate in this cross-sectional study. For data collection, The 25 item questionnaire of Likert scale type with four scales was used. Factor analysis was performed to define the patterns of self-treatment.</p> <p>Results</p> <p>398 patients participated in the study. The mean age of the study population was 54.9 ± 12.9 years. The majority (97%) had type 2 diabetes. 50% of patients reported self- treatment. The self-treatment score was 45.8 ± 8.8 (25-100). Female gender, lower education and co-morbid illnesses of hypertension, hyperlipidemia and cardiac disease had significant relationship with self-treatment. The factor analysis procedure revealed seven factors that explained the 43% of variation in the self-treatment. These seven factors were categorized as knowledge, deficiencies of formal treatments, available self-treatment methods, physician related factors, the tendency to use herbal remedies, underlying factors such as gender and factors related to diabetes.</p> <p>Conclusions</p> <p>There is a medium tendency for self-treatment in diabetic patients. The assessment of self-treatment practices must be an essential part of patients' management in diabetes care.</p
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